[v3] libstdc++/20534, debug mode vs. includes

[Gabriel Dos Reis]

Benjamin Kosnik <bkoz@redhat.com> writes:

| Hey dudes.
| 
| This bug is about how assert.h is included since 3.4, for most
| everything. This is a result of the debug mode implementation, but the
| solution is relatively straightforward. In addition, this re-work of
| debug.h makes a cleaner (IMHO) demarcation between the internal debug
| mode macros and the external, pre-process away to nothing macros.
| 
| This has been a relatively consistent portability annoyance for us.
| I've added a negative test so that we'll be alerted if this comes up
| again, in some other guise.
| 
| In addition, I found some other issues with the extension debug mode containers.
| 
| tested x86/linux
| tested x86/linux -D_GLIBCXX_DEBUG
| gcc
| gcc-4_0-branch

I like it! 

I have nto tested it, but I'm wondering what happens if I say

   g++ -D_GLIBCXX_DEBUG -DNDEBUG ....

-- Gaby